Resistance device



A. E. WALLER.

RESISTANCE DEVICE.

APPLICATION FILED MAR. 3. 1919. 1,373,689. Patented Apr. 5, 1921. I 2 SHEETS-SHEET I;

I A. E. WALLER.

RESISTANCE DEVICE.

APPLICATION FILED MAR.3, 1919. 1,373,689. Patented Apr. 5, 1921.

2 SHEETS-SHEET 2.

re si'rss PTENT OFFER.

ALFRED E. WALLER, 0F l -KOUN'I VERNON, NEW YORK, ASSIGNOR TO WARD LEONARD ELECTRIC COMPANY, .zi. CORPORATION 035 NEW YORK.

RESISTANCE DEVICE.

is a specification.

This invention relates to electrical resistance devices and particularly to the current carrying resistor elements of rheostats and the like. 7 Que object of the invention is to provide a resistance device in which. the

resistor units will be strong, light and selfsupporting and readily adaptable to a-wide variety of uses.

In my invention I employ resistor elements of thin strip metal shaped to be permanently rigid and self-supporting when in place and yetallowing for free expansion and contraction under temperature changes. At the same time the shaping of the units is such that before assembly and attachment they are easily flexed into different forms :to be variously positioned and combined to meet gdifferent' commercial requirements.

Other advantages of this invention especially in cheapness of manufacture and durability in'servicewill appear from the following description of various embodiments taken in connection with the accompanying drawings in which- Figures 1, 2, 3 and 4 are perspective views showingthe formation of a resistor element for one embodiment of the invention.

Fig. '5 is a plan view with top removed of a rheostat showing one embodiment of my invention. i

Fi 6 is a vertical section of Fig. 5.

Fig. 7 is diagram illustrating the resistor element connections of the rheostat of Figs. 5 and 6. r Figs. 8 and 9 are rear andside views respectively in vertical section of another em bodiment of the invention.

Fig. 10' is a perspective view of a detail of the apparatus of Figs. 8 and 9.

- Figs. 11 and 12 are rear and side views re spectively illustrating another modified form of resistance embodying the invention.

Fig. 13 is adiagram illustrating a further modification of the invention to form a fixed resistance unit.

Fig. 14- is a plan view of another embodi $pecificati0n 01 Letters Patent.

Patented Apr. 5, 1921.

Appfication filed March 3, 1919. Serial No. 280,293.

ment of the invention illustrating a further modification, and

Fig. 15 is a perspective view of a resistor elementof the modification of Fig. 14.

In the embodiments of the invention illustrated in the drawings the resistor element for the rheostat or other resistance device is formed from a continuous strip or ribbon 20 of resistant metal of suitable cross section, fromwhich the resistor element may be formed and cut ofl at a single operation,

or it maybe formed in the successive steps shown in Figs. 1 to 4 of the drawing. The metal strip is longitudinally stiffened as by turning up the side flanges 21, and at certain desired portions as 23, 24 and 25, Fig. 3, are provided flat, unstifi'ened relatively flexible sections which: are bent to form the piece into a unit of resistor element such as shown in Fig. 4; having longitudinally stiff supporting portions 26, 27 and adjacent flexed portions to permit the stiflened portions and the end points of attachment to be variously adjusted. The relative number and arrangement of the flexed and stiff portions in each element may be widely varied. In the form of resistor unit shown, Fig. l, a middle bend 24 intervenes between the ends 23 and 25 which in assembled posi tion form feet providedwith holes 28, 29 for fastening to posts or taps on a rigid base. The two channeled legs 26 and 27 of the V are stifl in all directions and are connected by the portion 24; made rigid by its connecting position between the solidly held leg portions. When. thus attached the unit unyieldingly holds its shape against strain in any direction and is completely self-supporting. 1 At the same time it permits of free expansion and contraction under temperawithout troublesome allowances for diflerg ing lengths. The unit is also easily attached in place onpanel boards or panel strips and easily fitted to. different arrangements of binding posts or taps as shown in Figs. 5 to 15 of the drawings, so that the structure and assembly of the entire resistance device is made' simple and easy and a single line of standard units may be used in different types of resistance devices.

In Figs. 5 and 6 the resistance device or vention comprises a casing within which is the vertical panel 31 arrying on its front face the controller arm and contactsSQ, a id on its rear face the resistor elements 3?, 39 connected to contacts as indicated in diagram in F 7. The current passes from one terminal 36 through the permanent or residual resistor elements 37 in series on posts a, Z), 0, etc, and thence to the post Z and such of the resistor elements 39 on posts 7 m, a, etc. as are iifei'posed in the t'll'Cult by the position of the controller arm which is pivoted at 8% and connected to th other terminal 40.

The resistance units 3'7, 39 are of the type illustrated in F 4 and are assembled in series on posts or taps carried by the panel 31. The elements 37 a e sig-Zagged back and forth in series between posts (a, o, G etc, ant have their eet- 23, 25, fastened to said posts which are so spaced that where two feet of adjacent elements are fastened to the nine post the legs have to be twisted aroune their longitudinal axes as shown at to bring the overlapping feet at right angles to each other and avoid interference. Similarly the elements 59 are connected in series to the posts m, a, etc. with their channeled portions twisted to put their ends on the posts. T his twist accommodates the units to a close spacing of the posts and is readily given to the unit less when trey e be ng assembled,

since the channeled stiffening s l leaves the le easily twisted, while the curved mte mediate head is stiff against such twistin r c: and is not warped thereby.

For eer ain cases where it is desirable to assemble the units very close togetha and where excepti rigidity is desired H1681- mediate bends of the resistor units may be separated by insula ing washers thread :d on rods 4" passing through these end bends an l. insuh 15,5 sleeves may also be proyinec on the rod and between the washers to insulate the units from the rods. lVith nuts l8 set to bind these parts together a unitary rigil 1 rut-tare is formed in which each part supports ever other yet all are free to expand contract under temperature changes. resistors are uniformly spaced and well ilated and it is obvious that with this eiinstruetion anothe' opposite board I e A; nbined with rows of resistors oppositely rested and intervening between the ones tively to resistor units 55, 56 57, 58 at the re: of the panel by posts passing th 'ough the panel. These posts long enoi to properly spread the ends of the 'esistor units which a connected zig-zag to the end etone post and base of the next as shown in perspective in l 10 where the first unit is connected to the end oi? post 5i, the remaining units being similarly connected. T ie other oi resist-or elements 56 57 and 58 are similarly connected to their respecines of posts all: as to elements 56 and sets overlap at the center with set set This overlap econom'zes space and is accon plished by relatively h using each set elements or by spacing the end perforations iarthcr from the middle bend. In this modification oi? the invention the ends oi the elements i re elan'iped between nuts (it) and spaced mart by sleeves fi ting on the nests and sleeves are o'r' sulliciently sinall dia1nit between the side flanges 21 so that mges may be carried to the extreme of the Through the outer ends of or elements threaded a c-:;-n'=.ie -ting irrying spools 66 15)) insuthe elements from the rod and disks rt-inn the elements i t of elements is sepa s JDOIZlnO and all 2-.1

as necessary t "e changes wit'iout s I by pieces the rows or contacts.

id 12 the support 70 has i s front tame and co;

I i 7 )osts '43 to which the To SO pporting lo ed to a post. In this e emenls in series va'her so that a e saine strip ('5 separating the In fermio r, resistors 21 series of t with other sinof the men 1 strip concutting and later cut into clusters of the desired number of units which would be bent into the series of loops fitted onto tsie posts. i

In Fig. 13 number of such clusters are shown assembled in a different manner to form a permanent resistance between terminals S0 and 86. In this modification two successive units are formed integrally at such locations as between points 101 and 102. e being only a single thickness of metal under the intermediate clamping nut a row Or alternatino' 87. Thus the part between points 101 and 102 maybe said to be W-shaped.

In Figs. 14 and 15 resistor units 89 of this invention are illustrated connected to a series ofclosely spaced taps 90, 91, 92, 93, etc., arranged on the are of a circle m for cooperation with a pivoted controller arm. Tn thisv modification the elements extend at right angles to the base 96 and the legs 94: of the elements must be considerably twisted around their longitudinal axes as shown in Fig. 15 with the feet 95 brought close together in a very compact manner.

It will. be seen that my improved resistor elements are'free' from the disadvantages attending the use of flexible wires or strips which are not effectively self-supporting and may require insulating supports and spacers. Also my resistor elements are not subject to the risk of breakage like cast metal grids, and they can be made thinner in cross section and hence of higher resistance and lighter weight than for cast metal grids.

The resistor element of this invention is easily and cheaply. manufactured. The stock is plain ribbon of any suitable metal or resistance alloy. From this there is ma chine formed the complete resistor by simple bending and cutting operations involving no wastage'of metal. The final shape of the resistor element is such that it may be directly formed from the strip and the units are assembled simply by fastening them in place on the posts without any special holding-means or supporting frames. and with out complicated folding or soldering of the units in place. The intermediate flexed portion and the stiffened legs permit the unit to be adapted to a wide variety of uses while assuring a rigidly self-supporting yet freely expanding and contracting structure when assembled. A single line of resistor stock serves for many different devices reducing the amount of stock to be kept on hand. The preferred flanged channel form of stiffening is simple to make and of great strengthening effect compacting the strip in section and permitting the stock to be very thin and of great area and radiating power. In

many types of devices such asthose in Figs. 8 to '15 these resistor elements may be directly fastened to the contact taps without intervening leads and this together with the absence of spaced supporting frame work produces a simple, lightand highly efficient construction.

1 claim r 1. In a resistance device, a supporting panel, a plurality of resistor elements comprising strips having stiffened lengthwise portions connected by unstiffened bent portions, and supports for said strips mounted on said panel laterally displaced from each other and connected with the ends of said strips, which ends are separated from said bent portions by the intervening stiffened lengthwise portions.

2. In' a resistance device, a supporting panel, a plurality of resistor elements of bent strip metal comprising self-supporting stiffened lengthwise portions extending at an angle to each other and having flexible connections between said stiffened portions permitting relative positioning and free expansion and contraction of said stiffened portions, and laterally spaced supports on said panel for supporting said strips.

8. In a resistance device, a supporting panel, a plurality of resistor elements extending outwardly from said panel comprising supporting end portions with stiffened lengthwise portions intervening between said end portions, and unstiffened bent portions intervening between said stiffened portions, andlaterally spaced supports on said panel for supporting said elements by engagement with said end portions.

4. In a resistance device, a supporting panel, a resistor element outwardly extending from said panel, comprising an integral ribbon of metal bent to form stiffened lengthwise portions, and an unstiffened portion intervening between said stiffened portions so that said stiffened portions may be relatively positioned by bending said unstiffened ortion and su o orts on said Janel for said element laterally spaced from each other and connected to portions of said ribbon which are separated from said unstiffened bent portion by the intervening stiffened lengthwise portions.

' 5. In a resistance device, a supporting panel, a resistor element having stiffened lengthwise portions at an angle to each other and having a connecting relatively flexible portion between said stifiened portions adapted to bend to permit relative positioning and free expansion and contraction of said stiffened portions, and supports for said element on said panel spaced from each other and located at the separated ends of the angularly related stiffened portions of said element.

6. In a resistance device, a panel, a plurality of rows of posts on said panel, and resistance elements attached to said posts, said elements having self-supporting lengthwise portions outwardly extending fromv thin narrow sheet metal strip bent with respect to a longitudinal axis to give it stiffness, and bent with respect to a transverse axis to space the longitudinal stiflened portions at an angle to each other to form a V- shaped element, a support, and means on said support to which the separated ends of said V-shaped element are connected:

8. A resistance device comprising a supporting panel, posts mounted on said panel and spaced from each other, a plurality of resistance elements of long thin narrow sheet metal having two points of each of said elements attached respectively to said posts, each of said elements having longitudinal portions extending outwardly from said panel and bent with respect to a longitudinal axis to give it stiffness and bent at an intermediate portion with respect to a transverse axis and having the longitudinal portions spaced at an angle to each other, each of said elements being'supported on said posts at the most widely separated points of the element, and a movable contact device for varying the number of said elements in circuit.

9. A resistance device comprising'a supporting panel, two. sets of posts mounted on said panel, a plurality of resistance elements supported by said posts, each of said elements extending outwardly from said panel and comprising a thin metal strip having stiffened lengthwise portions connected together at their outer ends, said stiffened portions being angularly related to each other and having the separated ends of said elements connected respectively to one of the posts of each of said sets 10. A resistance device comprising a panel, twoposts on said panel, and a V- shaped metal strip having the legs bent longitudinally to form stiffened portions connected together at the apex and extending outwardly from said panel, each of said legs being bent at the separated ends of the element to form a supporting foot extending parallel to the plane of said panel, said feet being connected respectively to said posts.

11. A resistance device comprising a panel, two sets of posts on said panel, and a resistance element of metal ribbon comprising stiffened portions having their edges flanged at an angle'to the body of the ribbon and an intermediate unflanged portion bent to position said stiffened portions at an angle to each other, the widely separated portions of said angularly related stiffened portions being connected respectively to said sets of posts.

12. A resistance device comprising a panel, two sets of posts on said panel, and resistance elements supported by said posts, each of said elements extending outwardly from said panel in a plane substantially perpendicular thereto and comprising longitudinally stiffened metal strips forming lengthwise portions at an angle to each other and connected at their outer ends and supported at their inner separated ends on said two sets of posts respectively.

13. A resistance device comprising a panel, a plurality of posts on said panel spaced from each other, resistance strips supported on said posts and extending outwardly from the back of said panel and having longitudinal portions of thin metal strips longitudinally stiffenedand connected at their outer ends and having their inner ends mounted on said posts, and a movable contact device on the front of said panel for varying the amount of resistance in circuit.

14:. A resistor element adapted to be formed from a metal ribbon and comprising portions longitudinally stiffened and con nected by a plane bend, said stiffened portions being twisted around their longitudinal axes without warping said bend, and means for connecting said stifiened portions to'a support.

15. A resistor element adapted to be formed from metal ribbon and comprising portions longitudinally stiffened and connected by a plane bend, said stiffened portions being twisted around their longitudinal axes without warping said bend, and

means for connecting said stiffened portions to a support comprising relatively flexible feet members extending from the ends of said portions.

=16. In a resistance device the combination with a plurality of taps in the same plane, of resistor elements connected to said taps and extending perpendicular to said plane comprising portions attached to said taps, self supporting legs extending from said attached portions and bent portions connecting said legs.

17. In a resistance device the combination with a series of taps, of resistor elements connected between said taps and comprising longitudinally stiffened portions twisted to fit in place on said taps.

18. In a resistance device the combination with rows of taps in a plane, of resistance elements connected between said rows and extending perpendicularly to said plane comprising portions attachedto said taps and V shaped stiffened portions connecting said attached portions.

ALFRED E. WALLER. 

